North Korea on Thursday demanded the lifting of United Nations sanctions and an end to joint American-South Korean military exercises as preconditions for starting dialogue to defuse tension on the Korean Peninsula. By making demands that both the United States and South Korea had no intention of accepting, North Korea signaled that it would not stand down anytime soon from a military standoff that has lasted for weeks. But the fact that North Korea has recently begun responding to American and South Korean offers for dialogue, even though they came with steep preconditions, has raised cautious hopes among South Korean analysts that the North might be ready to wind down weeks of hostile rhetoric th...